Automatic heater control valve



- April 1,8, 1944.

.1. B. wrm-TED 'AUTOMATIC HEATER CONTROL VALVE Filed sept.` 17, 1942 3 sheets-sheet 1 April 18, 1944. I J. B. wHn-TED *2,347,142

' 4 AUTOMATIC HEATER CONTROL VALVE Filed sept. 17, -1942 s sheets-sheet 2 April 1s, 1944. 1B, WHITTE@ 2,347,142

AUTOMATIC HEATER CONTROL VALVE Filed Sept'. 17, 1942 3 Sheets-Sheet 3 9290 1,30 30 o 114 O66' M1126 3 62 /10 4 24 6 XX C) fo il 24' Zaz/QJZZ'OI? Jan/2. Mzfzed Patented Apr., 18, 1944 2,347,142 p AUTOMATIC HEATER CONTROL VALVE John B. Whitted, Evanston, Ill., assigner to `Stewart-Warner Corporation,

ration of Virginia Chicago, Ill., a corpo- Application September 17, 1942, Serial No. 458,637

s claims. rc1. asv-12.3)

My invention pertains to automatic heater control valves and is more particularly concerned with the provision of a valve for controlling the exhaust from an internal combustion type of heater used on aircraft.

It has become common practice to utilize a portion of the fuel and air mixture supplied to the aircraft engine by its supercharger as a source of combustible mixture for the operation of one or more internal combustion type heaters for heating the cabin and other parts of the aircraft. The products of combustion from the heater have ordinarily been discharged overboard, but in some instances have been returned to the inlet of the supercharger. Under some'conditions of operation of the aircraft, it is desirable to utilize differential pressure between the inlet and the outlet of the supercharger to cause flow of the combustible mixture to the heater and to cause the discharge of the products of combustion therefrom, while under other conditions of operation, the pressure differential between the pressure side of the supercharger and the atmosphere is suilicient for satisfactory operation of the heater.

Although under substantially all conditions of aircraft operation, the heater will operate satisfactorily when it is connected between-the outlet and the inletpf the engine supercharger, there is some slight disadvantage in permanently connecting the heater in this manner. Even though the products of combustion entering the inlet of the supercharger from the heater form but a small percentage of the flow through the supercharger, and the dilution of the mixture supplied to the engine or engines therefore does not noticeably aiect engine operation, such dilution may have some effect on engine operation -or, over a long period of time, on the life of the4 supercharger and engineparts. It is, therefore advisable to avoid such admixture of the products of combustion from the heater with the charge flowing to the engine whenever this is possible. ,l

It is, therefore, an object of my invention to provide improved means for automatically controlling the flow of exhaust gases from an internal combustion type heater, either to the atmcsphere or to the inlet side of the engine supercharger, depending upon the conditions under which the aircraft is operating.

A yfurther object of my invention is to provide an improved diverter valve having 'a more sensitive control means. Y

Other objects and advantages will appear from.

the following description, reference being had to the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of a typical installation embodying my invention;

Fig. 2 is a plan view of my novel automatic control valve;

Fig. 3 is an end view of the control valve shown in Fig. 2; and

Fig. 4 is an enlarged view similar to Fig. 2

but showing parts in section to illustrate constructional features.

Inv Fig. 1, I have shown an aircraft heating system comprising an internal combustion type heater I0 which may be of any suitable construction, such, for example, as that shown in the copending application of` H. J DeN. McCollum, Serial No. 447,345, led June 7, 1942. y

This heater is illustrated as being supplied with a combustible mixture of fuel and air through a conduit I2 which receives the mixture from the pressure side of a supercharger I4 serving to supply a combustible mixture to an engine or engines through a conduit I6. The mixture is supplied to the supercharger I4 through an induction pipe I8 which may be controlled by a throttle valve 20.

The products of combustion are discharged from. the heater I0 into an exhaust pipe 22 lead'- ing to the inlet 24 of my novel automatic control valve 26. This valve has an outlet 28, illustrated as being connected to atmosphere by a tail pipe 30 and a second outlet 32 connected to the supercharger induction pipe I8 by conduit 34. The tail pipe 30 is illustrated as projecting through the skin 36 of the aircraft so that operation of the aircraft creates a suction at the outlet end of the tail pipe 30, although this particular arrangement of the tail pipe is not essential to my invention and other arrangements of the tail pipe may be used in lieu thereof.

The control valvev 26 is a three-way valve wherein communication between the inlet 24 and the outlet 28, or the outlet 32, is regulated by a valve disc 38 mounted on a shaft 40 and rotated by an arm 42 between the position shown in Fig.

`1 wherein the inlet 24 is in connection with the `outlet 28 and a second position which connects the inlet 24 with the outlet 32. The position of the valve disc 38 is controlled by the difference in pressure between the heater inlet pipe or manifold I2 and the atmosphere in such manner that when'this pressure differential issulcient to provide the necessary flow of combustible mixture into and through the heater I 0, the products of combustion from the heater are discharged through the tail pipe 80, whereas when this differential pressure is insufllcient for this purpose, the valve disc 881s shifted Vfrom the position shown in Fig. 1 to a second position connecting the valve inlet 24 with the valve outlet 32 to cause the products of combustion from the heater to be discharged into the induction pipe I8 of the supercharger I4,

In general, the control means for the valve disc l 38 comprises a control diaphragm 44 located in a primary control chamber 46 connected by pipe 48 to the heater manifold I2. That part of the chamber 46 on the other side of the diaphragm is open to atmosphere so that one side ofthe diaphgram 44 is exposed to the pressure at the heater inlet and the other side of this diaphragm is exposed to atmospheric pressure. Light springs tend to resist movement of the diaphragm 44 under the pressure created by the supercharger in the heater inlet conduit or manifold I2.

The control diaphragm regulates theposition of a secondary control mechanism 52 regulating the admission of suction and pressure to opposite sides of a motor diaphragm 54. The motor diaphragm 54 is connected by linkage 56 to the struction. In this Fig. 4, the control diaphragm- 44 forms part of a primary control mechanism, including the diaphragm chamber 46 formed by stampings 60 and 62 which are clamped'against opposite sides of the diaphragm 44 by studs 64 threaded into a clamping ring 66. The central .portion of the diaphragm 44 is reinforced by metal plates 68 and 'I0 clamped to opposite sides of the diaphragm 44 by the riveted end 'I2l of a valve member 14, which is reciprocated by movement of the central portion of the diaphragm.

The stamping 62 is provided with a threaded fitting 'I6 to which is connected the pipe 48 leading to the heater intake conduit or manifold I2, so that the right hand side of the diaphragm 44, as viewed in Fig. 4, is exposed to the pressure created by the supercharger I4. The stamping 60 is provided with a central opening 18 in which thevalve member 'I4 is located. This opening 'I8 provides free communication between the lefthand side of the diaphragm chamber and the interior of a housing 80, so that pressure on the lefthand side of the diaphragm varies with variations of the pressure in the housing 80. This housing is open to atmosphere, so that the control diaphragm 44 is subjected to the differential in pressure existing between the manifold I2 and atmosphere.

The valve member 'I4 has a cylindrical valve portion 82 which slides in the bore 84 of a casting 86 and this valve member and casting form nate sets of passages for alternatively connecting ,these ports with opposite sides of the motor diaphragm 54 located in a diaphragm chamber |00 formed between castings |02 and |04 and provided with fluid .passages |06 and |08. The passage |06 connects with a passage ||0 in the casting 86 to form conduit 59A and the passage |08 communicates with a passage |I2 in this casting to form conduit'59. The passages IIO and II2 have ports I|4 and IIB, respectively. When the valve member14 is in the position shown, diagonal passage I I8 connects ports ||4 and 94 so that the lefthand side of motor diaphragm 54 is subjected to the suction at the intake side of the supercharger I4. At .the same time, diagonal passage |20 connects ports 88 and ||6 so that the righthand side of the motor passage |24 connects ports 94 and I6 to reverseof the supercharger.

the application of atmospheric pressure and suction to the motor diaphragm 54. The valve member 14 is urged toward the right by springs |26 which-rest upon the oppositely directed arms |28 of support |30. This support is press tted onto the end of casting 86 and secures housing 80 thereto. This support is also provided with hol- .loW posts |32 to which the stamping 60 is secured by screws |34. 1

The motor diaphragm 54 has reinforcing plates |36 and |38 on opposite sides of its central portion and secured to the diaphragm by the riveted end |40 of a piston rod |42 forming part of the linkage 56 for connecting the motor diaphragm 54 with the arm 42 attached to the shaft 40 of the valve disc 38. The casting |04 is mounted on the control valve housing |44 and is attached by studs |46 to supports |48 carried by the housing |44.

When the pressure differential between the combustible mixture supplied to the heater through conduit I2 and-atmosphere is suflciently great to overcome the resistance of springs |26, control diaphragm 44 and valve member 14 are moved to the left, as viewed in Fig. 4, whereupon passage |22 connectsiports 88 and ||4 and the lefthand side of the motor diaphragm 54 is exposed to the pressure created at the outlet side At the Sametime, passage |24 connects ports 94 and ||6 so that the righthand side of the diaphragm 54 is exposed to the parts of the secondary control mechanism 52 forl reversing the direction of power application to the motor diaphragm 54. The casting 86 has a port 88 communicating with the passage 90 in a f nipple 92 to which is connected the pipe 58 leading to the outlet side of the supercharger I4. The casting 86 has a second :port 94 connected to the passage 96 in a nipple 98 to which is connected suction created at the intake side of the supercharger. The pressure differential between opposite sides of the motor diaphragm 54 then moves this diaphragm to the right, as viewed in Fig. 4,

and shifts the valve disc 88 from the position shown in Fig. 1 to a :position wherein the heater discharge pipe 22 is in communication with tail pipe 30.

The parts remain in this position as long as the pressure differential between heater supply pipe I2 and atmosphere is suicient to overcome the force of springs |26.y As soon as this pressure differential decreases to such an extent as to impair heater operation, springs |26 move control diaphragm 44 and valve member 'I4 to the right -and return it to the position shown in Fig. 4. In

this position the righthand side of motor diaphragm 54 is exposed to the super-atmospheric the motor diaphragm 54 to move to the left, as4 viewed in Fig. 4, and to shift valve disc 38 to the' position shown in Fig. 1 so that the products of combustion discharged from the heater I flow from discharge pipe 28 into pipe 34 leading to the intake side of the supercharger I4.

An important feature of my invention lies in the arrangement of the springs |26 so that the valve member is operated with a snap action in both directions and can not stop in mid-position. The springs |26 are bowed to suchV an extent that they exert the greatest force on the valve member 'i4 when the springs are in the expanded position shown in Fig. 4. As the pressure in the heater manifold l2 increases, it approaches the 4predetermined operating pressure, such, for example, as two pounds above atmospheric pressure.

. When this predetermined pressure is reached in the heater manifold I2 and that portion of the diaphragm chamber 46 which is to the right of the diaphragm 44, the resistance of springs |26 is overcome and valve member 14 moves toward the left. This movement increases the curvature of springs |26 and reduces their resistance to movement of the valve member 14 and this decreasing resistance of the springs |26 continues as the valve member moves toward its full lefthand position. The force necessary to create the r initial lefthand movement of the valve member I4 is, therefore, more than sufiicient to complete this movement and the movement once initiated is always completed.

If we assume that a pressure of two pounds above atmosphere on the righthand side of diaphragm 44 was sufficient to initiate lefthand movement of valve member 14, a lesser pressure, such as 1% pounds above atmospheric pressure, on the righthand side of the diaphragm 44 will be suiiicient to retain valve member 14 in its left-- hand position. 'Ihe initiating pressure would ordinarily be less than the pressure in the heater manifold 2 under normal operating conditions, so that after the valve member 14 had been moved to the left (Fig. 4) to connect the heater exhaust with the tail pipe 3U, the pressure in the heater manifold |2 would increase, but such in crease would have no affect on the primary control. If the pressure in the heater manifold I2 dropped belou7 1% pounds above atmospheric pressure, springs |26 would move valve member 14 to the right, as viewed in Fig. 4. The force exerted by the springs |26 on the valve member 'I4 would increase continuously as the valve member moved to the right, with the result that the valve member 'lwould be snapped back to the position shown in Fig. 4 andthe motor diaphragm 54 would be actuated to shift the valve disc 38 to connect the heater exhaust with the induction pipe of the supercharger I4.

It will be noted that the primary control consisting of the control diaphragm 44 and its associated parts is entirely separate and distinct from the motor mechanism for shifting the valve disc 38. The primary control. therefore, can be made of any suitable size and the springs |26 given any desired tension toenable the primary control to function properly under any predetermined pressure differential. The Imotor mechanism for shifting the valve disc 38 may also be made of any size so that it will produce any desired force under any given pressure differential. The primary control functions onlyto shift a cylindrical valve part which is inherentlybalanced and requires a minimum of force so that this primary control may be made extremely sensitive, and while I have described my novel control valve as being utilized for a particular purpose, it is capable of other uses and is not to be considered as limited to the particular use described herein.

While this application illustrates and describes only a'single embodiment of my invention, my lnventionfis not limited to this particular embodiment shown but may assume numerous forms and is to be construed as including all modifications and variations falling within `the scope of the appended claims.

`I claim:

1. A heater control valve for an aircraft heater of the internal combustion type supplied with combustible mixture from a supercharger and adapted to exhaust alternatively through a tail pipe or through a. pipe, leading to the 4intake of the supercharger, said valve comprising a valve disc for controlling communication between said heater and said alternative pipes, a primary control operative in response to differences in pressure between the fuel inlet for said heater and atmosphere, fluid motor mechanism for shifting l said valve disc, said motor mechanism including a diaphragm operated by fluid pressure across said supercharger and means responsive to said primary control for actuating said motor mechanism and valve disc in opposite directions'.

2. A heater control valve for an aircraft heater of the internal combustion type supplied with combustible mixture from a supercharger and adapted to exhaust either through a tail pipe or through a pipe leading to the intake of the supercharger, said valve comprising a valve disc for controlling communication between said heater and said pipes, a primary control operative in response to differences in pressure between the fuel inlet for said heater and atmosphere, double acting iiuid motor mechanism of the variable chamber type for shifting said valve disc, and valve means responsive to said primary control for actuating said motor mechanism in opposite directions.

3. A heater control valve for an aircraft heater of the internal combustion type supplied with combustible mixture from a supercharger and adapted to exhaust either through a tail pipe ,or through a pipe leading to the intake of the supercharger, said valve comprising a valve member for selectively controlling communication between said heater and said pipes, primary control means operative in response to differences in pressure between the fuel inlet for said heater and atmosphere, a fluid motor operative bythe pressure difference across said supercharger for shifting said valve disc, and a secondary control mechanism responsive to said primary control means for actuating said motor in opposite directions.

4. A heater control valve for a heater of the internal combustion .type supplied with combustible mixture from a supercharger and adapted to exhaust alternatively through a tail pipe or through a pipe leading to the intake of the supercharger, said valve comprising a valve disc for controlling communication between said heater and said alternative pipes, a control diaphragm operative in response to differences in pressure between the fuel inlet for said heater and atmosphere, a motor diaphragm for shifting said valve disc, and means responsive to said primary control for actuating said motor diaphragm in opposite directions. 4

5. 'A heater control valve for a heater of the internal combustion type supplied with combustible mixture trompa supercharger and adapted to exhaust valternatively through a tail pipe or through a pipe leading to the intake of the supercharger, said valve comprising a valve member for controlling communication between said heater and said alternative pipes, a motor for shifting said valve member, means connecting said motor to said supercharger for actuation thereby, and automatic control means responsive to pressure differences between the heatery inlet means.

6. A heater control valve for a-heater of the internal combustion type supplied with combustible mixture fromva supercharger andadapted to exhaust alternatively through a tail pipe or through a pipe leading to the intake of the supercharger,A said valve comprising a valve member for controlling communication between said alternative pipes, a motor for shifting said valve last-named means responsive to pressure diii'erences between the heater inlet and atmosphere.

JOHN B. WHIT'I'ED. 

